1 //===- ConstantFold.cpp - LLVM constant folder ----------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements folding of constants for LLVM. This implements the
11 // (internal) ConstantFold.h interface, which is used by the
12 // ConstantExpr::get* methods to automatically fold constants when possible.
14 // The current constant folding implementation is implemented in two pieces: the
15 // template-based folder for simple primitive constants like ConstantInt, and
16 // the special case hackery that we use to symbolically evaluate expressions
17 // that use ConstantExprs.
19 //===----------------------------------------------------------------------===//
21 #include "ConstantFold.h"
22 #include "llvm/Constants.h"
23 #include "llvm/Instructions.h"
24 #include "llvm/DerivedTypes.h"
25 #include "llvm/Function.h"
26 #include "llvm/GlobalAlias.h"
27 #include "llvm/ADT/SmallVector.h"
28 #include "llvm/Support/Compiler.h"
29 #include "llvm/Support/GetElementPtrTypeIterator.h"
30 #include "llvm/Support/ManagedStatic.h"
31 #include "llvm/Support/MathExtras.h"
35 //===----------------------------------------------------------------------===//
36 // ConstantFold*Instruction Implementations
37 //===----------------------------------------------------------------------===//
39 /// BitCastConstantVector - Convert the specified ConstantVector node to the
40 /// specified vector type. At this point, we know that the elements of the
41 /// input vector constant are all simple integer or FP values.
42 static Constant *BitCastConstantVector(ConstantVector *CV,
43 const VectorType *DstTy,
45 // If this cast changes element count then we can't handle it here:
46 // doing so requires endianness information. This should be handled by
47 // Analysis/ConstantFolding.cpp
48 unsigned NumElts = DstTy->getNumElements();
49 if (NumElts != CV->getNumOperands())
52 // Check to verify that all elements of the input are simple.
53 for (unsigned i = 0; i != NumElts; ++i) {
54 if (!isa<ConstantInt>(CV->getOperand(i)) &&
55 !isa<ConstantFP>(CV->getOperand(i)))
59 // Bitcast each element now.
60 std::vector<Constant*> Result;
61 const Type *DstEltTy = DstTy->getElementType();
62 for (unsigned i = 0; i != NumElts; ++i)
63 Result.push_back(ConstantExpr::getBitCast(CV->getOperand(i), DstEltTy));
64 return ConstantVector::get(Result, locked);
67 /// This function determines which opcode to use to fold two constant cast
68 /// expressions together. It uses CastInst::isEliminableCastPair to determine
69 /// the opcode. Consequently its just a wrapper around that function.
70 /// @brief Determine if it is valid to fold a cast of a cast
73 unsigned opc, ///< opcode of the second cast constant expression
74 const ConstantExpr*Op, ///< the first cast constant expression
75 const Type *DstTy ///< desintation type of the first cast
77 assert(Op && Op->isCast() && "Can't fold cast of cast without a cast!");
78 assert(DstTy && DstTy->isFirstClassType() && "Invalid cast destination type");
79 assert(CastInst::isCast(opc) && "Invalid cast opcode");
81 // The the types and opcodes for the two Cast constant expressions
82 const Type *SrcTy = Op->getOperand(0)->getType();
83 const Type *MidTy = Op->getType();
84 Instruction::CastOps firstOp = Instruction::CastOps(Op->getOpcode());
85 Instruction::CastOps secondOp = Instruction::CastOps(opc);
87 // Let CastInst::isEliminableCastPair do the heavy lifting.
88 return CastInst::isEliminableCastPair(firstOp, secondOp, SrcTy, MidTy, DstTy,
92 static Constant *FoldBitCast(Constant *V, const Type *DestTy,
94 const Type *SrcTy = V->getType();
96 return V; // no-op cast
98 // Check to see if we are casting a pointer to an aggregate to a pointer to
99 // the first element. If so, return the appropriate GEP instruction.
100 if (const PointerType *PTy = dyn_cast<PointerType>(V->getType()))
101 if (const PointerType *DPTy = dyn_cast<PointerType>(DestTy))
102 if (PTy->getAddressSpace() == DPTy->getAddressSpace()) {
103 SmallVector<Value*, 8> IdxList;
104 IdxList.push_back(Constant::getNullValue(Type::Int32Ty, locked));
105 const Type *ElTy = PTy->getElementType();
106 while (ElTy != DPTy->getElementType()) {
107 if (const StructType *STy = dyn_cast<StructType>(ElTy)) {
108 if (STy->getNumElements() == 0) break;
109 ElTy = STy->getElementType(0);
110 IdxList.push_back(Constant::getNullValue(Type::Int32Ty));
111 } else if (const SequentialType *STy =
112 dyn_cast<SequentialType>(ElTy)) {
113 if (isa<PointerType>(ElTy)) break; // Can't index into pointers!
114 ElTy = STy->getElementType();
115 IdxList.push_back(IdxList[0]);
121 if (ElTy == DPTy->getElementType())
122 return ConstantExpr::getGetElementPtr(V, &IdxList[0],
123 IdxList.size(), locked);
126 // Handle casts from one vector constant to another. We know that the src
127 // and dest type have the same size (otherwise its an illegal cast).
128 if (const VectorType *DestPTy = dyn_cast<VectorType>(DestTy)) {
129 if (const VectorType *SrcTy = dyn_cast<VectorType>(V->getType())) {
130 assert(DestPTy->getBitWidth() == SrcTy->getBitWidth() &&
131 "Not cast between same sized vectors!");
133 // First, check for null. Undef is already handled.
134 if (isa<ConstantAggregateZero>(V))
135 return Constant::getNullValue(DestTy, locked);
137 if (ConstantVector *CV = dyn_cast<ConstantVector>(V))
138 return BitCastConstantVector(CV, DestPTy, locked);
141 // Canonicalize scalar-to-vector bitcasts into vector-to-vector bitcasts
142 // This allows for other simplifications (although some of them
143 // can only be handled by Analysis/ConstantFolding.cpp).
144 if (isa<ConstantInt>(V) || isa<ConstantFP>(V))
145 return ConstantExpr::getBitCast(ConstantVector::get(&V, 1, locked),
149 // Finally, implement bitcast folding now. The code below doesn't handle
151 if (isa<ConstantPointerNull>(V)) // ptr->ptr cast.
152 return ConstantPointerNull::get(cast<PointerType>(DestTy), locked);
154 // Handle integral constant input.
155 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
156 if (DestTy->isInteger())
157 // Integral -> Integral. This is a no-op because the bit widths must
158 // be the same. Consequently, we just fold to V.
161 if (DestTy->isFloatingPoint())
162 return ConstantFP::get(APFloat(CI->getValue(),
163 DestTy != Type::PPC_FP128Ty), locked);
165 // Otherwise, can't fold this (vector?)
169 // Handle ConstantFP input.
170 if (const ConstantFP *FP = dyn_cast<ConstantFP>(V))
172 return ConstantInt::get(FP->getValueAPF().bitcastToAPInt(), locked);
178 Constant *llvm::ConstantFoldCastInstruction(unsigned opc, const Constant *V,
179 const Type *DestTy, bool locked) {
180 if (isa<UndefValue>(V)) {
181 // zext(undef) = 0, because the top bits will be zero.
182 // sext(undef) = 0, because the top bits will all be the same.
183 // [us]itofp(undef) = 0, because the result value is bounded.
184 if (opc == Instruction::ZExt || opc == Instruction::SExt ||
185 opc == Instruction::UIToFP || opc == Instruction::SIToFP)
186 return Constant::getNullValue(DestTy, locked);
187 return UndefValue::get(DestTy, locked);
189 // No compile-time operations on this type yet.
190 if (V->getType() == Type::PPC_FP128Ty || DestTy == Type::PPC_FP128Ty)
193 // If the cast operand is a constant expression, there's a few things we can
194 // do to try to simplify it.
195 if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) {
197 // Try hard to fold cast of cast because they are often eliminable.
198 if (unsigned newOpc = foldConstantCastPair(opc, CE, DestTy))
199 return ConstantExpr::getCast(newOpc, CE->getOperand(0), DestTy, locked);
200 } else if (CE->getOpcode() == Instruction::GetElementPtr) {
201 // If all of the indexes in the GEP are null values, there is no pointer
202 // adjustment going on. We might as well cast the source pointer.
203 bool isAllNull = true;
204 for (unsigned i = 1, e = CE->getNumOperands(); i != e; ++i)
205 if (!CE->getOperand(i)->isNullValue()) {
210 // This is casting one pointer type to another, always BitCast
211 return ConstantExpr::getPointerCast(CE->getOperand(0), DestTy, locked);
215 // If the cast operand is a constant vector, perform the cast by
216 // operating on each element. In the cast of bitcasts, the element
217 // count may be mismatched; don't attempt to handle that here.
218 if (const ConstantVector *CV = dyn_cast<ConstantVector>(V))
219 if (isa<VectorType>(DestTy) &&
220 cast<VectorType>(DestTy)->getNumElements() ==
221 CV->getType()->getNumElements()) {
222 std::vector<Constant*> res;
223 const VectorType *DestVecTy = cast<VectorType>(DestTy);
224 const Type *DstEltTy = DestVecTy->getElementType();
225 for (unsigned i = 0, e = CV->getType()->getNumElements(); i != e; ++i)
226 res.push_back(ConstantExpr::getCast(opc,
227 CV->getOperand(i), DstEltTy, locked));
228 return ConstantVector::get(DestVecTy, res, locked);
231 // We actually have to do a cast now. Perform the cast according to the
234 case Instruction::FPTrunc:
235 case Instruction::FPExt:
236 if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V)) {
238 APFloat Val = FPC->getValueAPF();
239 Val.convert(DestTy == Type::FloatTy ? APFloat::IEEEsingle :
240 DestTy == Type::DoubleTy ? APFloat::IEEEdouble :
241 DestTy == Type::X86_FP80Ty ? APFloat::x87DoubleExtended :
242 DestTy == Type::FP128Ty ? APFloat::IEEEquad :
244 APFloat::rmNearestTiesToEven, &ignored);
245 return ConstantFP::get(Val, locked);
247 return 0; // Can't fold.
248 case Instruction::FPToUI:
249 case Instruction::FPToSI:
250 if (const ConstantFP *FPC = dyn_cast<ConstantFP>(V)) {
251 const APFloat &V = FPC->getValueAPF();
254 uint32_t DestBitWidth = cast<IntegerType>(DestTy)->getBitWidth();
255 (void) V.convertToInteger(x, DestBitWidth, opc==Instruction::FPToSI,
256 APFloat::rmTowardZero, &ignored);
257 APInt Val(DestBitWidth, 2, x);
258 return ConstantInt::get(Val, locked);
260 return 0; // Can't fold.
261 case Instruction::IntToPtr: //always treated as unsigned
262 if (V->isNullValue()) // Is it an integral null value?
263 return ConstantPointerNull::get(cast<PointerType>(DestTy), locked);
264 return 0; // Other pointer types cannot be casted
265 case Instruction::PtrToInt: // always treated as unsigned
266 if (V->isNullValue()) // is it a null pointer value?
267 return ConstantInt::get(DestTy, 0, locked);
268 return 0; // Other pointer types cannot be casted
269 case Instruction::UIToFP:
270 case Instruction::SIToFP:
271 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
272 APInt api = CI->getValue();
273 const uint64_t zero[] = {0, 0};
274 APFloat apf = APFloat(APInt(DestTy->getPrimitiveSizeInBits(),
276 (void)apf.convertFromAPInt(api,
277 opc==Instruction::SIToFP,
278 APFloat::rmNearestTiesToEven);
279 return ConstantFP::get(apf, locked);
282 case Instruction::ZExt:
283 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
284 uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth();
285 APInt Result(CI->getValue());
286 Result.zext(BitWidth);
287 return ConstantInt::get(Result, locked);
290 case Instruction::SExt:
291 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
292 uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth();
293 APInt Result(CI->getValue());
294 Result.sext(BitWidth);
295 return ConstantInt::get(Result, locked);
298 case Instruction::Trunc:
299 if (const ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
300 uint32_t BitWidth = cast<IntegerType>(DestTy)->getBitWidth();
301 APInt Result(CI->getValue());
302 Result.trunc(BitWidth);
303 return ConstantInt::get(Result, locked);
306 case Instruction::BitCast:
307 return FoldBitCast(const_cast<Constant*>(V), DestTy, locked);
309 assert(!"Invalid CE CastInst opcode");
313 assert(0 && "Failed to cast constant expression");
317 Constant *llvm::ConstantFoldSelectInstruction(const Constant *Cond,
319 const Constant *V2, bool locked) {
320 if (const ConstantInt *CB = dyn_cast<ConstantInt>(Cond))
321 return const_cast<Constant*>(CB->getZExtValue() ? V1 : V2);
323 if (isa<UndefValue>(V1)) return const_cast<Constant*>(V2);
324 if (isa<UndefValue>(V2)) return const_cast<Constant*>(V1);
325 if (isa<UndefValue>(Cond)) return const_cast<Constant*>(V1);
326 if (V1 == V2) return const_cast<Constant*>(V1);
330 Constant *llvm::ConstantFoldExtractElementInstruction(const Constant *Val,
331 const Constant *Idx) {
332 if (isa<UndefValue>(Val)) // ee(undef, x) -> undef
333 return UndefValue::get(cast<VectorType>(Val->getType())->getElementType());
334 if (Val->isNullValue()) // ee(zero, x) -> zero
335 return Constant::getNullValue(
336 cast<VectorType>(Val->getType())->getElementType());
338 if (const ConstantVector *CVal = dyn_cast<ConstantVector>(Val)) {
339 if (const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx)) {
340 return CVal->getOperand(CIdx->getZExtValue());
341 } else if (isa<UndefValue>(Idx)) {
342 // ee({w,x,y,z}, undef) -> w (an arbitrary value).
343 return CVal->getOperand(0);
349 Constant *llvm::ConstantFoldInsertElementInstruction(const Constant *Val,
351 const Constant *Idx) {
352 const ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx);
354 APInt idxVal = CIdx->getValue();
355 if (isa<UndefValue>(Val)) {
356 // Insertion of scalar constant into vector undef
357 // Optimize away insertion of undef
358 if (isa<UndefValue>(Elt))
359 return const_cast<Constant*>(Val);
360 // Otherwise break the aggregate undef into multiple undefs and do
363 cast<VectorType>(Val->getType())->getNumElements();
364 std::vector<Constant*> Ops;
366 for (unsigned i = 0; i < numOps; ++i) {
368 (idxVal == i) ? Elt : UndefValue::get(Elt->getType());
369 Ops.push_back(const_cast<Constant*>(Op));
371 return ConstantVector::get(Ops);
373 if (isa<ConstantAggregateZero>(Val)) {
374 // Insertion of scalar constant into vector aggregate zero
375 // Optimize away insertion of zero
376 if (Elt->isNullValue())
377 return const_cast<Constant*>(Val);
378 // Otherwise break the aggregate zero into multiple zeros and do
381 cast<VectorType>(Val->getType())->getNumElements();
382 std::vector<Constant*> Ops;
384 for (unsigned i = 0; i < numOps; ++i) {
386 (idxVal == i) ? Elt : Constant::getNullValue(Elt->getType());
387 Ops.push_back(const_cast<Constant*>(Op));
389 return ConstantVector::get(Ops);
391 if (const ConstantVector *CVal = dyn_cast<ConstantVector>(Val)) {
392 // Insertion of scalar constant into vector constant
393 std::vector<Constant*> Ops;
394 Ops.reserve(CVal->getNumOperands());
395 for (unsigned i = 0; i < CVal->getNumOperands(); ++i) {
397 (idxVal == i) ? Elt : cast<Constant>(CVal->getOperand(i));
398 Ops.push_back(const_cast<Constant*>(Op));
400 return ConstantVector::get(Ops);
406 /// GetVectorElement - If C is a ConstantVector, ConstantAggregateZero or Undef
407 /// return the specified element value. Otherwise return null.
408 static Constant *GetVectorElement(const Constant *C, unsigned EltNo) {
409 if (const ConstantVector *CV = dyn_cast<ConstantVector>(C))
410 return CV->getOperand(EltNo);
412 const Type *EltTy = cast<VectorType>(C->getType())->getElementType();
413 if (isa<ConstantAggregateZero>(C))
414 return Constant::getNullValue(EltTy);
415 if (isa<UndefValue>(C))
416 return UndefValue::get(EltTy);
420 Constant *llvm::ConstantFoldShuffleVectorInstruction(const Constant *V1,
422 const Constant *Mask) {
423 // Undefined shuffle mask -> undefined value.
424 if (isa<UndefValue>(Mask)) return UndefValue::get(V1->getType());
426 unsigned MaskNumElts = cast<VectorType>(Mask->getType())->getNumElements();
427 unsigned SrcNumElts = cast<VectorType>(V1->getType())->getNumElements();
428 const Type *EltTy = cast<VectorType>(V1->getType())->getElementType();
430 // Loop over the shuffle mask, evaluating each element.
431 SmallVector<Constant*, 32> Result;
432 for (unsigned i = 0; i != MaskNumElts; ++i) {
433 Constant *InElt = GetVectorElement(Mask, i);
434 if (InElt == 0) return 0;
436 if (isa<UndefValue>(InElt))
437 InElt = UndefValue::get(EltTy);
438 else if (ConstantInt *CI = dyn_cast<ConstantInt>(InElt)) {
439 unsigned Elt = CI->getZExtValue();
440 if (Elt >= SrcNumElts*2)
441 InElt = UndefValue::get(EltTy);
442 else if (Elt >= SrcNumElts)
443 InElt = GetVectorElement(V2, Elt - SrcNumElts);
445 InElt = GetVectorElement(V1, Elt);
446 if (InElt == 0) return 0;
451 Result.push_back(InElt);
454 return ConstantVector::get(&Result[0], Result.size());
457 Constant *llvm::ConstantFoldExtractValueInstruction(const Constant *Agg,
458 const unsigned *Idxs,
460 // Base case: no indices, so return the entire value.
462 return const_cast<Constant *>(Agg);
464 if (isa<UndefValue>(Agg)) // ev(undef, x) -> undef
465 return UndefValue::get(ExtractValueInst::getIndexedType(Agg->getType(),
469 if (isa<ConstantAggregateZero>(Agg)) // ev(0, x) -> 0
471 Constant::getNullValue(ExtractValueInst::getIndexedType(Agg->getType(),
475 // Otherwise recurse.
476 return ConstantFoldExtractValueInstruction(Agg->getOperand(*Idxs),
480 Constant *llvm::ConstantFoldInsertValueInstruction(const Constant *Agg,
482 const unsigned *Idxs,
484 // Base case: no indices, so replace the entire value.
486 return const_cast<Constant *>(Val);
488 if (isa<UndefValue>(Agg)) {
489 // Insertion of constant into aggregate undef
490 // Optimize away insertion of undef
491 if (isa<UndefValue>(Val))
492 return const_cast<Constant*>(Agg);
493 // Otherwise break the aggregate undef into multiple undefs and do
495 const CompositeType *AggTy = cast<CompositeType>(Agg->getType());
497 if (const ArrayType *AR = dyn_cast<ArrayType>(AggTy))
498 numOps = AR->getNumElements();
500 numOps = cast<StructType>(AggTy)->getNumElements();
501 std::vector<Constant*> Ops(numOps);
502 for (unsigned i = 0; i < numOps; ++i) {
503 const Type *MemberTy = AggTy->getTypeAtIndex(i);
506 ConstantFoldInsertValueInstruction(UndefValue::get(MemberTy),
507 Val, Idxs+1, NumIdx-1) :
508 UndefValue::get(MemberTy);
509 Ops[i] = const_cast<Constant*>(Op);
511 if (isa<StructType>(AggTy))
512 return ConstantStruct::get(Ops);
514 return ConstantArray::get(cast<ArrayType>(AggTy), Ops);
516 if (isa<ConstantAggregateZero>(Agg)) {
517 // Insertion of constant into aggregate zero
518 // Optimize away insertion of zero
519 if (Val->isNullValue())
520 return const_cast<Constant*>(Agg);
521 // Otherwise break the aggregate zero into multiple zeros and do
523 const CompositeType *AggTy = cast<CompositeType>(Agg->getType());
525 if (const ArrayType *AR = dyn_cast<ArrayType>(AggTy))
526 numOps = AR->getNumElements();
528 numOps = cast<StructType>(AggTy)->getNumElements();
529 std::vector<Constant*> Ops(numOps);
530 for (unsigned i = 0; i < numOps; ++i) {
531 const Type *MemberTy = AggTy->getTypeAtIndex(i);
534 ConstantFoldInsertValueInstruction(Constant::getNullValue(MemberTy),
535 Val, Idxs+1, NumIdx-1) :
536 Constant::getNullValue(MemberTy);
537 Ops[i] = const_cast<Constant*>(Op);
539 if (isa<StructType>(AggTy))
540 return ConstantStruct::get(Ops);
542 return ConstantArray::get(cast<ArrayType>(AggTy), Ops);
544 if (isa<ConstantStruct>(Agg) || isa<ConstantArray>(Agg)) {
545 // Insertion of constant into aggregate constant
546 std::vector<Constant*> Ops(Agg->getNumOperands());
547 for (unsigned i = 0; i < Agg->getNumOperands(); ++i) {
550 ConstantFoldInsertValueInstruction(Agg->getOperand(i),
551 Val, Idxs+1, NumIdx-1) :
553 Ops[i] = const_cast<Constant*>(Op);
556 if (isa<StructType>(Agg->getType()))
557 C = ConstantStruct::get(Ops);
559 C = ConstantArray::get(cast<ArrayType>(Agg->getType()), Ops);
566 /// EvalVectorOp - Given two vector constants and a function pointer, apply the
567 /// function pointer to each element pair, producing a new ConstantVector
568 /// constant. Either or both of V1 and V2 may be NULL, meaning a
569 /// ConstantAggregateZero operand.
570 static Constant *EvalVectorOp(const ConstantVector *V1,
571 const ConstantVector *V2,
572 const VectorType *VTy,
573 Constant *(*FP)(Constant*, Constant*, bool)) {
574 std::vector<Constant*> Res;
575 const Type *EltTy = VTy->getElementType();
576 for (unsigned i = 0, e = VTy->getNumElements(); i != e; ++i) {
577 const Constant *C1 = V1 ? V1->getOperand(i) : Constant::getNullValue(EltTy);
578 const Constant *C2 = V2 ? V2->getOperand(i) : Constant::getNullValue(EltTy);
579 Res.push_back(FP(const_cast<Constant*>(C1),
580 const_cast<Constant*>(C2), true));
582 return ConstantVector::get(Res);
585 Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
589 // No compile-time operations on this type yet.
590 if (C1->getType() == Type::PPC_FP128Ty)
593 // Handle UndefValue up front
594 if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) {
596 case Instruction::Xor:
597 if (isa<UndefValue>(C1) && isa<UndefValue>(C2))
598 // Handle undef ^ undef -> 0 special case. This is a common
600 return Constant::getNullValue(C1->getType(), locked);
602 case Instruction::Add:
603 case Instruction::Sub:
604 return UndefValue::get(C1->getType(), locked);
605 case Instruction::Mul:
606 case Instruction::And:
607 return Constant::getNullValue(C1->getType(), locked);
608 case Instruction::UDiv:
609 case Instruction::SDiv:
610 case Instruction::URem:
611 case Instruction::SRem:
612 if (!isa<UndefValue>(C2)) // undef / X -> 0
613 return Constant::getNullValue(C1->getType(), locked);
614 return const_cast<Constant*>(C2); // X / undef -> undef
615 case Instruction::Or: // X | undef -> -1
616 if (const VectorType *PTy = dyn_cast<VectorType>(C1->getType()))
617 return ConstantVector::getAllOnesValue(PTy, locked);
618 return ConstantInt::getAllOnesValue(C1->getType(), locked);
619 case Instruction::LShr:
620 if (isa<UndefValue>(C2) && isa<UndefValue>(C1))
621 return const_cast<Constant*>(C1); // undef lshr undef -> undef
622 return Constant::getNullValue(C1->getType(), locked); // X lshr undef -> 0
624 case Instruction::AShr:
625 if (!isa<UndefValue>(C2))
626 return const_cast<Constant*>(C1); // undef ashr X --> undef
627 else if (isa<UndefValue>(C1))
628 return const_cast<Constant*>(C1); // undef ashr undef -> undef
630 return const_cast<Constant*>(C1); // X ashr undef --> X
631 case Instruction::Shl:
632 // undef << X -> 0 or X << undef -> 0
633 return Constant::getNullValue(C1->getType(), locked);
637 // Handle simplifications of the RHS when a constant int.
638 if (const ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) {
640 case Instruction::Add:
641 if (CI2->equalsInt(0)) return const_cast<Constant*>(C1); // X + 0 == X
643 case Instruction::Sub:
644 if (CI2->equalsInt(0)) return const_cast<Constant*>(C1); // X - 0 == X
646 case Instruction::Mul:
647 if (CI2->equalsInt(0)) return const_cast<Constant*>(C2); // X * 0 == 0
648 if (CI2->equalsInt(1))
649 return const_cast<Constant*>(C1); // X * 1 == X
651 case Instruction::UDiv:
652 case Instruction::SDiv:
653 if (CI2->equalsInt(1))
654 return const_cast<Constant*>(C1); // X / 1 == X
655 if (CI2->equalsInt(0))
656 return UndefValue::get(CI2->getType()); // X / 0 == undef
658 case Instruction::URem:
659 case Instruction::SRem:
660 if (CI2->equalsInt(1))
661 return Constant::getNullValue(CI2->getType()); // X % 1 == 0
662 if (CI2->equalsInt(0))
663 return UndefValue::get(CI2->getType()); // X % 0 == undef
665 case Instruction::And:
666 if (CI2->isZero()) return const_cast<Constant*>(C2); // X & 0 == 0
667 if (CI2->isAllOnesValue())
668 return const_cast<Constant*>(C1); // X & -1 == X
670 if (const ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1)) {
671 // (zext i32 to i64) & 4294967295 -> (zext i32 to i64)
672 if (CE1->getOpcode() == Instruction::ZExt) {
673 unsigned DstWidth = CI2->getType()->getBitWidth();
675 CE1->getOperand(0)->getType()->getPrimitiveSizeInBits();
676 APInt PossiblySetBits(APInt::getLowBitsSet(DstWidth, SrcWidth));
677 if ((PossiblySetBits & CI2->getValue()) == PossiblySetBits)
678 return const_cast<Constant*>(C1);
681 // If and'ing the address of a global with a constant, fold it.
682 if (CE1->getOpcode() == Instruction::PtrToInt &&
683 isa<GlobalValue>(CE1->getOperand(0))) {
684 GlobalValue *GV = cast<GlobalValue>(CE1->getOperand(0));
686 // Functions are at least 4-byte aligned.
687 unsigned GVAlign = GV->getAlignment();
688 if (isa<Function>(GV))
689 GVAlign = std::max(GVAlign, 4U);
692 unsigned DstWidth = CI2->getType()->getBitWidth();
693 unsigned SrcWidth = std::min(DstWidth, Log2_32(GVAlign));
694 APInt BitsNotSet(APInt::getLowBitsSet(DstWidth, SrcWidth));
696 // If checking bits we know are clear, return zero.
697 if ((CI2->getValue() & BitsNotSet) == CI2->getValue())
698 return Constant::getNullValue(CI2->getType());
703 case Instruction::Or:
704 if (CI2->equalsInt(0)) return const_cast<Constant*>(C1); // X | 0 == X
705 if (CI2->isAllOnesValue())
706 return const_cast<Constant*>(C2); // X | -1 == -1
708 case Instruction::Xor:
709 if (CI2->equalsInt(0)) return const_cast<Constant*>(C1); // X ^ 0 == X
711 case Instruction::AShr:
712 // ashr (zext C to Ty), C2 -> lshr (zext C, CSA), C2
713 if (const ConstantExpr *CE1 = dyn_cast<ConstantExpr>(C1))
714 if (CE1->getOpcode() == Instruction::ZExt) // Top bits known zero.
715 return ConstantExpr::getLShr(const_cast<Constant*>(C1),
716 const_cast<Constant*>(C2));
721 // At this point we know neither constant is an UndefValue.
722 if (const ConstantInt *CI1 = dyn_cast<ConstantInt>(C1)) {
723 if (const ConstantInt *CI2 = dyn_cast<ConstantInt>(C2)) {
724 using namespace APIntOps;
725 const APInt &C1V = CI1->getValue();
726 const APInt &C2V = CI2->getValue();
730 case Instruction::Add:
731 return ConstantInt::get(C1V + C2V);
732 case Instruction::Sub:
733 return ConstantInt::get(C1V - C2V);
734 case Instruction::Mul:
735 return ConstantInt::get(C1V * C2V);
736 case Instruction::UDiv:
737 assert(!CI2->isNullValue() && "Div by zero handled above");
738 return ConstantInt::get(C1V.udiv(C2V));
739 case Instruction::SDiv:
740 assert(!CI2->isNullValue() && "Div by zero handled above");
741 if (C2V.isAllOnesValue() && C1V.isMinSignedValue())
742 return UndefValue::get(CI1->getType()); // MIN_INT / -1 -> undef
743 return ConstantInt::get(C1V.sdiv(C2V));
744 case Instruction::URem:
745 assert(!CI2->isNullValue() && "Div by zero handled above");
746 return ConstantInt::get(C1V.urem(C2V));
747 case Instruction::SRem:
748 assert(!CI2->isNullValue() && "Div by zero handled above");
749 if (C2V.isAllOnesValue() && C1V.isMinSignedValue())
750 return UndefValue::get(CI1->getType()); // MIN_INT % -1 -> undef
751 return ConstantInt::get(C1V.srem(C2V));
752 case Instruction::And:
753 return ConstantInt::get(C1V & C2V);
754 case Instruction::Or:
755 return ConstantInt::get(C1V | C2V);
756 case Instruction::Xor:
757 return ConstantInt::get(C1V ^ C2V);
758 case Instruction::Shl: {
759 uint32_t shiftAmt = C2V.getZExtValue();
760 if (shiftAmt < C1V.getBitWidth())
761 return ConstantInt::get(C1V.shl(shiftAmt));
763 return UndefValue::get(C1->getType()); // too big shift is undef
765 case Instruction::LShr: {
766 uint32_t shiftAmt = C2V.getZExtValue();
767 if (shiftAmt < C1V.getBitWidth())
768 return ConstantInt::get(C1V.lshr(shiftAmt));
770 return UndefValue::get(C1->getType()); // too big shift is undef
772 case Instruction::AShr: {
773 uint32_t shiftAmt = C2V.getZExtValue();
774 if (shiftAmt < C1V.getBitWidth())
775 return ConstantInt::get(C1V.ashr(shiftAmt));
777 return UndefValue::get(C1->getType()); // too big shift is undef
781 } else if (const ConstantFP *CFP1 = dyn_cast<ConstantFP>(C1)) {
782 if (const ConstantFP *CFP2 = dyn_cast<ConstantFP>(C2)) {
783 APFloat C1V = CFP1->getValueAPF();
784 APFloat C2V = CFP2->getValueAPF();
785 APFloat C3V = C1V; // copy for modification
789 case Instruction::FAdd:
790 (void)C3V.add(C2V, APFloat::rmNearestTiesToEven);
791 return ConstantFP::get(C3V);
792 case Instruction::FSub:
793 (void)C3V.subtract(C2V, APFloat::rmNearestTiesToEven);
794 return ConstantFP::get(C3V);
795 case Instruction::FMul:
796 (void)C3V.multiply(C2V, APFloat::rmNearestTiesToEven);
797 return ConstantFP::get(C3V);
798 case Instruction::FDiv:
799 (void)C3V.divide(C2V, APFloat::rmNearestTiesToEven);
800 return ConstantFP::get(C3V);
801 case Instruction::FRem:
802 (void)C3V.mod(C2V, APFloat::rmNearestTiesToEven);
803 return ConstantFP::get(C3V);
806 } else if (const VectorType *VTy = dyn_cast<VectorType>(C1->getType())) {
807 const ConstantVector *CP1 = dyn_cast<ConstantVector>(C1);
808 const ConstantVector *CP2 = dyn_cast<ConstantVector>(C2);
809 if ((CP1 != NULL || isa<ConstantAggregateZero>(C1)) &&
810 (CP2 != NULL || isa<ConstantAggregateZero>(C2))) {
814 case Instruction::Add:
815 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getAdd);
816 case Instruction::FAdd:
817 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getFAdd);
818 case Instruction::Sub:
819 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getSub);
820 case Instruction::FSub:
821 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getFSub);
822 case Instruction::Mul:
823 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getMul);
824 case Instruction::FMul:
825 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getFMul);
826 case Instruction::UDiv:
827 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getUDiv);
828 case Instruction::SDiv:
829 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getSDiv);
830 case Instruction::FDiv:
831 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getFDiv);
832 case Instruction::URem:
833 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getURem);
834 case Instruction::SRem:
835 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getSRem);
836 case Instruction::FRem:
837 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getFRem);
838 case Instruction::And:
839 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getAnd);
840 case Instruction::Or:
841 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getOr);
842 case Instruction::Xor:
843 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getXor);
844 case Instruction::LShr:
845 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getLShr);
846 case Instruction::AShr:
847 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getAShr);
848 case Instruction::Shl:
849 return EvalVectorOp(CP1, CP2, VTy, ConstantExpr::getShl);
854 if (isa<ConstantExpr>(C1)) {
855 // There are many possible foldings we could do here. We should probably
856 // at least fold add of a pointer with an integer into the appropriate
857 // getelementptr. This will improve alias analysis a bit.
858 } else if (isa<ConstantExpr>(C2)) {
859 // If C2 is a constant expr and C1 isn't, flop them around and fold the
860 // other way if possible.
862 case Instruction::Add:
863 case Instruction::FAdd:
864 case Instruction::Mul:
865 case Instruction::FMul:
866 case Instruction::And:
867 case Instruction::Or:
868 case Instruction::Xor:
869 // No change of opcode required.
870 return ConstantFoldBinaryInstruction(Opcode, C2, C1);
872 case Instruction::Shl:
873 case Instruction::LShr:
874 case Instruction::AShr:
875 case Instruction::Sub:
876 case Instruction::FSub:
877 case Instruction::SDiv:
878 case Instruction::UDiv:
879 case Instruction::FDiv:
880 case Instruction::URem:
881 case Instruction::SRem:
882 case Instruction::FRem:
883 default: // These instructions cannot be flopped around.
888 // We don't know how to fold this.
892 /// isZeroSizedType - This type is zero sized if its an array or structure of
893 /// zero sized types. The only leaf zero sized type is an empty structure.
894 static bool isMaybeZeroSizedType(const Type *Ty) {
895 if (isa<OpaqueType>(Ty)) return true; // Can't say.
896 if (const StructType *STy = dyn_cast<StructType>(Ty)) {
898 // If all of elements have zero size, this does too.
899 for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i)
900 if (!isMaybeZeroSizedType(STy->getElementType(i))) return false;
903 } else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
904 return isMaybeZeroSizedType(ATy->getElementType());
909 /// IdxCompare - Compare the two constants as though they were getelementptr
910 /// indices. This allows coersion of the types to be the same thing.
912 /// If the two constants are the "same" (after coersion), return 0. If the
913 /// first is less than the second, return -1, if the second is less than the
914 /// first, return 1. If the constants are not integral, return -2.
916 static int IdxCompare(Constant *C1, Constant *C2, const Type *ElTy) {
917 if (C1 == C2) return 0;
919 // Ok, we found a different index. If they are not ConstantInt, we can't do
920 // anything with them.
921 if (!isa<ConstantInt>(C1) || !isa<ConstantInt>(C2))
922 return -2; // don't know!
924 // Ok, we have two differing integer indices. Sign extend them to be the same
925 // type. Long is always big enough, so we use it.
926 if (C1->getType() != Type::Int64Ty)
927 C1 = ConstantExpr::getSExt(C1, Type::Int64Ty);
929 if (C2->getType() != Type::Int64Ty)
930 C2 = ConstantExpr::getSExt(C2, Type::Int64Ty);
932 if (C1 == C2) return 0; // They are equal
934 // If the type being indexed over is really just a zero sized type, there is
935 // no pointer difference being made here.
936 if (isMaybeZeroSizedType(ElTy))
939 // If they are really different, now that they are the same type, then we
940 // found a difference!
941 if (cast<ConstantInt>(C1)->getSExtValue() <
942 cast<ConstantInt>(C2)->getSExtValue())
948 /// evaluateFCmpRelation - This function determines if there is anything we can
949 /// decide about the two constants provided. This doesn't need to handle simple
950 /// things like ConstantFP comparisons, but should instead handle ConstantExprs.
951 /// If we can determine that the two constants have a particular relation to
952 /// each other, we should return the corresponding FCmpInst predicate,
953 /// otherwise return FCmpInst::BAD_FCMP_PREDICATE. This is used below in
954 /// ConstantFoldCompareInstruction.
956 /// To simplify this code we canonicalize the relation so that the first
957 /// operand is always the most "complex" of the two. We consider ConstantFP
958 /// to be the simplest, and ConstantExprs to be the most complex.
959 static FCmpInst::Predicate evaluateFCmpRelation(const Constant *V1,
960 const Constant *V2) {
961 assert(V1->getType() == V2->getType() &&
962 "Cannot compare values of different types!");
964 // No compile-time operations on this type yet.
965 if (V1->getType() == Type::PPC_FP128Ty)
966 return FCmpInst::BAD_FCMP_PREDICATE;
968 // Handle degenerate case quickly
969 if (V1 == V2) return FCmpInst::FCMP_OEQ;
971 if (!isa<ConstantExpr>(V1)) {
972 if (!isa<ConstantExpr>(V2)) {
973 // We distilled thisUse the standard constant folder for a few cases
975 Constant *C1 = const_cast<Constant*>(V1);
976 Constant *C2 = const_cast<Constant*>(V2);
977 R = dyn_cast<ConstantInt>(
978 ConstantExpr::getFCmp(FCmpInst::FCMP_OEQ, C1, C2));
979 if (R && !R->isZero())
980 return FCmpInst::FCMP_OEQ;
981 R = dyn_cast<ConstantInt>(
982 ConstantExpr::getFCmp(FCmpInst::FCMP_OLT, C1, C2));
983 if (R && !R->isZero())
984 return FCmpInst::FCMP_OLT;
985 R = dyn_cast<ConstantInt>(
986 ConstantExpr::getFCmp(FCmpInst::FCMP_OGT, C1, C2));
987 if (R && !R->isZero())
988 return FCmpInst::FCMP_OGT;
990 // Nothing more we can do
991 return FCmpInst::BAD_FCMP_PREDICATE;
994 // If the first operand is simple and second is ConstantExpr, swap operands.
995 FCmpInst::Predicate SwappedRelation = evaluateFCmpRelation(V2, V1);
996 if (SwappedRelation != FCmpInst::BAD_FCMP_PREDICATE)
997 return FCmpInst::getSwappedPredicate(SwappedRelation);
999 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a
1000 // constantexpr or a simple constant.
1001 const ConstantExpr *CE1 = cast<ConstantExpr>(V1);
1002 switch (CE1->getOpcode()) {
1003 case Instruction::FPTrunc:
1004 case Instruction::FPExt:
1005 case Instruction::UIToFP:
1006 case Instruction::SIToFP:
1007 // We might be able to do something with these but we don't right now.
1013 // There are MANY other foldings that we could perform here. They will
1014 // probably be added on demand, as they seem needed.
1015 return FCmpInst::BAD_FCMP_PREDICATE;
1018 /// evaluateICmpRelation - This function determines if there is anything we can
1019 /// decide about the two constants provided. This doesn't need to handle simple
1020 /// things like integer comparisons, but should instead handle ConstantExprs
1021 /// and GlobalValues. If we can determine that the two constants have a
1022 /// particular relation to each other, we should return the corresponding ICmp
1023 /// predicate, otherwise return ICmpInst::BAD_ICMP_PREDICATE.
1025 /// To simplify this code we canonicalize the relation so that the first
1026 /// operand is always the most "complex" of the two. We consider simple
1027 /// constants (like ConstantInt) to be the simplest, followed by
1028 /// GlobalValues, followed by ConstantExpr's (the most complex).
1030 static ICmpInst::Predicate evaluateICmpRelation(const Constant *V1,
1033 assert(V1->getType() == V2->getType() &&
1034 "Cannot compare different types of values!");
1035 if (V1 == V2) return ICmpInst::ICMP_EQ;
1037 if (!isa<ConstantExpr>(V1) && !isa<GlobalValue>(V1)) {
1038 if (!isa<GlobalValue>(V2) && !isa<ConstantExpr>(V2)) {
1039 // We distilled this down to a simple case, use the standard constant
1042 Constant *C1 = const_cast<Constant*>(V1);
1043 Constant *C2 = const_cast<Constant*>(V2);
1044 ICmpInst::Predicate pred = ICmpInst::ICMP_EQ;
1045 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
1046 if (R && !R->isZero())
1048 pred = isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
1049 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
1050 if (R && !R->isZero())
1052 pred = isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
1053 R = dyn_cast<ConstantInt>(ConstantExpr::getICmp(pred, C1, C2));
1054 if (R && !R->isZero())
1057 // If we couldn't figure it out, bail.
1058 return ICmpInst::BAD_ICMP_PREDICATE;
1061 // If the first operand is simple, swap operands.
1062 ICmpInst::Predicate SwappedRelation =
1063 evaluateICmpRelation(V2, V1, isSigned);
1064 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE)
1065 return ICmpInst::getSwappedPredicate(SwappedRelation);
1067 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(V1)) {
1068 if (isa<ConstantExpr>(V2)) { // Swap as necessary.
1069 ICmpInst::Predicate SwappedRelation =
1070 evaluateICmpRelation(V2, V1, isSigned);
1071 if (SwappedRelation != ICmpInst::BAD_ICMP_PREDICATE)
1072 return ICmpInst::getSwappedPredicate(SwappedRelation);
1074 return ICmpInst::BAD_ICMP_PREDICATE;
1077 // Now we know that the RHS is a GlobalValue or simple constant,
1078 // which (since the types must match) means that it's a ConstantPointerNull.
1079 if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
1080 // Don't try to decide equality of aliases.
1081 if (!isa<GlobalAlias>(CPR1) && !isa<GlobalAlias>(CPR2))
1082 if (!CPR1->hasExternalWeakLinkage() || !CPR2->hasExternalWeakLinkage())
1083 return ICmpInst::ICMP_NE;
1085 assert(isa<ConstantPointerNull>(V2) && "Canonicalization guarantee!");
1086 // GlobalVals can never be null. Don't try to evaluate aliases.
1087 if (!CPR1->hasExternalWeakLinkage() && !isa<GlobalAlias>(CPR1))
1088 return ICmpInst::ICMP_NE;
1091 // Ok, the LHS is known to be a constantexpr. The RHS can be any of a
1092 // constantexpr, a CPR, or a simple constant.
1093 const ConstantExpr *CE1 = cast<ConstantExpr>(V1);
1094 const Constant *CE1Op0 = CE1->getOperand(0);
1096 switch (CE1->getOpcode()) {
1097 case Instruction::Trunc:
1098 case Instruction::FPTrunc:
1099 case Instruction::FPExt:
1100 case Instruction::FPToUI:
1101 case Instruction::FPToSI:
1102 break; // We can't evaluate floating point casts or truncations.
1104 case Instruction::UIToFP:
1105 case Instruction::SIToFP:
1106 case Instruction::BitCast:
1107 case Instruction::ZExt:
1108 case Instruction::SExt:
1109 // If the cast is not actually changing bits, and the second operand is a
1110 // null pointer, do the comparison with the pre-casted value.
1111 if (V2->isNullValue() &&
1112 (isa<PointerType>(CE1->getType()) || CE1->getType()->isInteger())) {
1113 bool sgnd = isSigned;
1114 if (CE1->getOpcode() == Instruction::ZExt) isSigned = false;
1115 if (CE1->getOpcode() == Instruction::SExt) isSigned = true;
1116 return evaluateICmpRelation(CE1Op0,
1117 Constant::getNullValue(CE1Op0->getType()),
1121 // If the dest type is a pointer type, and the RHS is a constantexpr cast
1122 // from the same type as the src of the LHS, evaluate the inputs. This is
1123 // important for things like "icmp eq (cast 4 to int*), (cast 5 to int*)",
1124 // which happens a lot in compilers with tagged integers.
1125 if (const ConstantExpr *CE2 = dyn_cast<ConstantExpr>(V2))
1126 if (CE2->isCast() && isa<PointerType>(CE1->getType()) &&
1127 CE1->getOperand(0)->getType() == CE2->getOperand(0)->getType() &&
1128 CE1->getOperand(0)->getType()->isInteger()) {
1129 bool sgnd = isSigned;
1130 if (CE1->getOpcode() == Instruction::ZExt) isSigned = false;
1131 if (CE1->getOpcode() == Instruction::SExt) isSigned = true;
1132 return evaluateICmpRelation(CE1->getOperand(0), CE2->getOperand(0),
1137 case Instruction::GetElementPtr:
1138 // Ok, since this is a getelementptr, we know that the constant has a
1139 // pointer type. Check the various cases.
1140 if (isa<ConstantPointerNull>(V2)) {
1141 // If we are comparing a GEP to a null pointer, check to see if the base
1142 // of the GEP equals the null pointer.
1143 if (const GlobalValue *GV = dyn_cast<GlobalValue>(CE1Op0)) {
1144 if (GV->hasExternalWeakLinkage())
1145 // Weak linkage GVals could be zero or not. We're comparing that
1146 // to null pointer so its greater-or-equal
1147 return isSigned ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE;
1149 // If its not weak linkage, the GVal must have a non-zero address
1150 // so the result is greater-than
1151 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
1152 } else if (isa<ConstantPointerNull>(CE1Op0)) {
1153 // If we are indexing from a null pointer, check to see if we have any
1154 // non-zero indices.
1155 for (unsigned i = 1, e = CE1->getNumOperands(); i != e; ++i)
1156 if (!CE1->getOperand(i)->isNullValue())
1157 // Offsetting from null, must not be equal.
1158 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
1159 // Only zero indexes from null, must still be zero.
1160 return ICmpInst::ICMP_EQ;
1162 // Otherwise, we can't really say if the first operand is null or not.
1163 } else if (const GlobalValue *CPR2 = dyn_cast<GlobalValue>(V2)) {
1164 if (isa<ConstantPointerNull>(CE1Op0)) {
1165 if (CPR2->hasExternalWeakLinkage())
1166 // Weak linkage GVals could be zero or not. We're comparing it to
1167 // a null pointer, so its less-or-equal
1168 return isSigned ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE;
1170 // If its not weak linkage, the GVal must have a non-zero address
1171 // so the result is less-than
1172 return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
1173 } else if (const GlobalValue *CPR1 = dyn_cast<GlobalValue>(CE1Op0)) {
1175 // If this is a getelementptr of the same global, then it must be
1176 // different. Because the types must match, the getelementptr could
1177 // only have at most one index, and because we fold getelementptr's
1178 // with a single zero index, it must be nonzero.
1179 assert(CE1->getNumOperands() == 2 &&
1180 !CE1->getOperand(1)->isNullValue() &&
1181 "Suprising getelementptr!");
1182 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
1184 // If they are different globals, we don't know what the value is,
1185 // but they can't be equal.
1186 return ICmpInst::ICMP_NE;
1190 const ConstantExpr *CE2 = cast<ConstantExpr>(V2);
1191 const Constant *CE2Op0 = CE2->getOperand(0);
1193 // There are MANY other foldings that we could perform here. They will
1194 // probably be added on demand, as they seem needed.
1195 switch (CE2->getOpcode()) {
1197 case Instruction::GetElementPtr:
1198 // By far the most common case to handle is when the base pointers are
1199 // obviously to the same or different globals.
1200 if (isa<GlobalValue>(CE1Op0) && isa<GlobalValue>(CE2Op0)) {
1201 if (CE1Op0 != CE2Op0) // Don't know relative ordering, but not equal
1202 return ICmpInst::ICMP_NE;
1203 // Ok, we know that both getelementptr instructions are based on the
1204 // same global. From this, we can precisely determine the relative
1205 // ordering of the resultant pointers.
1208 // Compare all of the operands the GEP's have in common.
1209 gep_type_iterator GTI = gep_type_begin(CE1);
1210 for (;i != CE1->getNumOperands() && i != CE2->getNumOperands();
1212 switch (IdxCompare(CE1->getOperand(i), CE2->getOperand(i),
1213 GTI.getIndexedType())) {
1214 case -1: return isSigned ? ICmpInst::ICMP_SLT:ICmpInst::ICMP_ULT;
1215 case 1: return isSigned ? ICmpInst::ICMP_SGT:ICmpInst::ICMP_UGT;
1216 case -2: return ICmpInst::BAD_ICMP_PREDICATE;
1219 // Ok, we ran out of things they have in common. If any leftovers
1220 // are non-zero then we have a difference, otherwise we are equal.
1221 for (; i < CE1->getNumOperands(); ++i)
1222 if (!CE1->getOperand(i)->isNullValue()) {
1223 if (isa<ConstantInt>(CE1->getOperand(i)))
1224 return isSigned ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT;
1226 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal.
1229 for (; i < CE2->getNumOperands(); ++i)
1230 if (!CE2->getOperand(i)->isNullValue()) {
1231 if (isa<ConstantInt>(CE2->getOperand(i)))
1232 return isSigned ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT;
1234 return ICmpInst::BAD_ICMP_PREDICATE; // Might be equal.
1236 return ICmpInst::ICMP_EQ;
1245 return ICmpInst::BAD_ICMP_PREDICATE;
1248 Constant *llvm::ConstantFoldCompareInstruction(unsigned short pred,
1250 const Constant *C2) {
1251 // Fold FCMP_FALSE/FCMP_TRUE unconditionally.
1252 if (pred == FCmpInst::FCMP_FALSE) {
1253 if (const VectorType *VT = dyn_cast<VectorType>(C1->getType()))
1254 return Constant::getNullValue(VectorType::getInteger(VT));
1256 return ConstantInt::getFalse();
1259 if (pred == FCmpInst::FCMP_TRUE) {
1260 if (const VectorType *VT = dyn_cast<VectorType>(C1->getType()))
1261 return Constant::getAllOnesValue(VectorType::getInteger(VT));
1263 return ConstantInt::getTrue();
1266 // Handle some degenerate cases first
1267 if (isa<UndefValue>(C1) || isa<UndefValue>(C2)) {
1268 // vicmp/vfcmp -> [vector] undef
1269 if (const VectorType *VTy = dyn_cast<VectorType>(C1->getType()))
1270 return UndefValue::get(VectorType::getInteger(VTy));
1272 // icmp/fcmp -> i1 undef
1273 return UndefValue::get(Type::Int1Ty);
1276 // No compile-time operations on this type yet.
1277 if (C1->getType() == Type::PPC_FP128Ty)
1280 // icmp eq/ne(null,GV) -> false/true
1281 if (C1->isNullValue()) {
1282 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C2))
1283 // Don't try to evaluate aliases. External weak GV can be null.
1284 if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage()) {
1285 if (pred == ICmpInst::ICMP_EQ)
1286 return ConstantInt::getFalse();
1287 else if (pred == ICmpInst::ICMP_NE)
1288 return ConstantInt::getTrue();
1290 // icmp eq/ne(GV,null) -> false/true
1291 } else if (C2->isNullValue()) {
1292 if (const GlobalValue *GV = dyn_cast<GlobalValue>(C1))
1293 // Don't try to evaluate aliases. External weak GV can be null.
1294 if (!isa<GlobalAlias>(GV) && !GV->hasExternalWeakLinkage()) {
1295 if (pred == ICmpInst::ICMP_EQ)
1296 return ConstantInt::getFalse();
1297 else if (pred == ICmpInst::ICMP_NE)
1298 return ConstantInt::getTrue();
1302 if (isa<ConstantInt>(C1) && isa<ConstantInt>(C2)) {
1303 APInt V1 = cast<ConstantInt>(C1)->getValue();
1304 APInt V2 = cast<ConstantInt>(C2)->getValue();
1306 default: assert(0 && "Invalid ICmp Predicate"); return 0;
1307 case ICmpInst::ICMP_EQ: return ConstantInt::get(Type::Int1Ty, V1 == V2);
1308 case ICmpInst::ICMP_NE: return ConstantInt::get(Type::Int1Ty, V1 != V2);
1309 case ICmpInst::ICMP_SLT:return ConstantInt::get(Type::Int1Ty, V1.slt(V2));
1310 case ICmpInst::ICMP_SGT:return ConstantInt::get(Type::Int1Ty, V1.sgt(V2));
1311 case ICmpInst::ICMP_SLE:return ConstantInt::get(Type::Int1Ty, V1.sle(V2));
1312 case ICmpInst::ICMP_SGE:return ConstantInt::get(Type::Int1Ty, V1.sge(V2));
1313 case ICmpInst::ICMP_ULT:return ConstantInt::get(Type::Int1Ty, V1.ult(V2));
1314 case ICmpInst::ICMP_UGT:return ConstantInt::get(Type::Int1Ty, V1.ugt(V2));
1315 case ICmpInst::ICMP_ULE:return ConstantInt::get(Type::Int1Ty, V1.ule(V2));
1316 case ICmpInst::ICMP_UGE:return ConstantInt::get(Type::Int1Ty, V1.uge(V2));
1318 } else if (isa<ConstantFP>(C1) && isa<ConstantFP>(C2)) {
1319 APFloat C1V = cast<ConstantFP>(C1)->getValueAPF();
1320 APFloat C2V = cast<ConstantFP>(C2)->getValueAPF();
1321 APFloat::cmpResult R = C1V.compare(C2V);
1323 default: assert(0 && "Invalid FCmp Predicate"); return 0;
1324 case FCmpInst::FCMP_FALSE: return ConstantInt::getFalse();
1325 case FCmpInst::FCMP_TRUE: return ConstantInt::getTrue();
1326 case FCmpInst::FCMP_UNO:
1327 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered);
1328 case FCmpInst::FCMP_ORD:
1329 return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpUnordered);
1330 case FCmpInst::FCMP_UEQ:
1331 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered ||
1332 R==APFloat::cmpEqual);
1333 case FCmpInst::FCMP_OEQ:
1334 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpEqual);
1335 case FCmpInst::FCMP_UNE:
1336 return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpEqual);
1337 case FCmpInst::FCMP_ONE:
1338 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpLessThan ||
1339 R==APFloat::cmpGreaterThan);
1340 case FCmpInst::FCMP_ULT:
1341 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered ||
1342 R==APFloat::cmpLessThan);
1343 case FCmpInst::FCMP_OLT:
1344 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpLessThan);
1345 case FCmpInst::FCMP_UGT:
1346 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpUnordered ||
1347 R==APFloat::cmpGreaterThan);
1348 case FCmpInst::FCMP_OGT:
1349 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpGreaterThan);
1350 case FCmpInst::FCMP_ULE:
1351 return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpGreaterThan);
1352 case FCmpInst::FCMP_OLE:
1353 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpLessThan ||
1354 R==APFloat::cmpEqual);
1355 case FCmpInst::FCMP_UGE:
1356 return ConstantInt::get(Type::Int1Ty, R!=APFloat::cmpLessThan);
1357 case FCmpInst::FCMP_OGE:
1358 return ConstantInt::get(Type::Int1Ty, R==APFloat::cmpGreaterThan ||
1359 R==APFloat::cmpEqual);
1361 } else if (isa<VectorType>(C1->getType())) {
1362 SmallVector<Constant*, 16> C1Elts, C2Elts;
1363 C1->getVectorElements(C1Elts);
1364 C2->getVectorElements(C2Elts);
1366 // If we can constant fold the comparison of each element, constant fold
1367 // the whole vector comparison.
1368 SmallVector<Constant*, 4> ResElts;
1369 const Type *InEltTy = C1Elts[0]->getType();
1370 bool isFP = InEltTy->isFloatingPoint();
1371 const Type *ResEltTy = InEltTy;
1373 ResEltTy = IntegerType::get(InEltTy->getPrimitiveSizeInBits());
1375 for (unsigned i = 0, e = C1Elts.size(); i != e; ++i) {
1376 // Compare the elements, producing an i1 result or constant expr.
1379 C = ConstantExpr::getFCmp(pred, C1Elts[i], C2Elts[i]);
1381 C = ConstantExpr::getICmp(pred, C1Elts[i], C2Elts[i]);
1383 // If it is a bool or undef result, convert to the dest type.
1384 if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) {
1386 ResElts.push_back(Constant::getNullValue(ResEltTy));
1388 ResElts.push_back(Constant::getAllOnesValue(ResEltTy));
1389 } else if (isa<UndefValue>(C)) {
1390 ResElts.push_back(UndefValue::get(ResEltTy));
1396 if (ResElts.size() == C1Elts.size())
1397 return ConstantVector::get(&ResElts[0], ResElts.size());
1400 if (C1->getType()->isFloatingPoint()) {
1401 int Result = -1; // -1 = unknown, 0 = known false, 1 = known true.
1402 switch (evaluateFCmpRelation(C1, C2)) {
1403 default: assert(0 && "Unknown relation!");
1404 case FCmpInst::FCMP_UNO:
1405 case FCmpInst::FCMP_ORD:
1406 case FCmpInst::FCMP_UEQ:
1407 case FCmpInst::FCMP_UNE:
1408 case FCmpInst::FCMP_ULT:
1409 case FCmpInst::FCMP_UGT:
1410 case FCmpInst::FCMP_ULE:
1411 case FCmpInst::FCMP_UGE:
1412 case FCmpInst::FCMP_TRUE:
1413 case FCmpInst::FCMP_FALSE:
1414 case FCmpInst::BAD_FCMP_PREDICATE:
1415 break; // Couldn't determine anything about these constants.
1416 case FCmpInst::FCMP_OEQ: // We know that C1 == C2
1417 Result = (pred == FCmpInst::FCMP_UEQ || pred == FCmpInst::FCMP_OEQ ||
1418 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE ||
1419 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE);
1421 case FCmpInst::FCMP_OLT: // We know that C1 < C2
1422 Result = (pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE ||
1423 pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT ||
1424 pred == FCmpInst::FCMP_ULE || pred == FCmpInst::FCMP_OLE);
1426 case FCmpInst::FCMP_OGT: // We know that C1 > C2
1427 Result = (pred == FCmpInst::FCMP_UNE || pred == FCmpInst::FCMP_ONE ||
1428 pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT ||
1429 pred == FCmpInst::FCMP_UGE || pred == FCmpInst::FCMP_OGE);
1431 case FCmpInst::FCMP_OLE: // We know that C1 <= C2
1432 // We can only partially decide this relation.
1433 if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT)
1435 else if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT)
1438 case FCmpInst::FCMP_OGE: // We known that C1 >= C2
1439 // We can only partially decide this relation.
1440 if (pred == FCmpInst::FCMP_ULT || pred == FCmpInst::FCMP_OLT)
1442 else if (pred == FCmpInst::FCMP_UGT || pred == FCmpInst::FCMP_OGT)
1445 case ICmpInst::ICMP_NE: // We know that C1 != C2
1446 // We can only partially decide this relation.
1447 if (pred == FCmpInst::FCMP_OEQ || pred == FCmpInst::FCMP_UEQ)
1449 else if (pred == FCmpInst::FCMP_ONE || pred == FCmpInst::FCMP_UNE)
1454 // If we evaluated the result, return it now.
1456 if (const VectorType *VT = dyn_cast<VectorType>(C1->getType())) {
1458 return Constant::getNullValue(VectorType::getInteger(VT));
1460 return Constant::getAllOnesValue(VectorType::getInteger(VT));
1462 return ConstantInt::get(Type::Int1Ty, Result);
1466 // Evaluate the relation between the two constants, per the predicate.
1467 int Result = -1; // -1 = unknown, 0 = known false, 1 = known true.
1468 switch (evaluateICmpRelation(C1, C2, CmpInst::isSigned(pred))) {
1469 default: assert(0 && "Unknown relational!");
1470 case ICmpInst::BAD_ICMP_PREDICATE:
1471 break; // Couldn't determine anything about these constants.
1472 case ICmpInst::ICMP_EQ: // We know the constants are equal!
1473 // If we know the constants are equal, we can decide the result of this
1474 // computation precisely.
1475 Result = (pred == ICmpInst::ICMP_EQ ||
1476 pred == ICmpInst::ICMP_ULE ||
1477 pred == ICmpInst::ICMP_SLE ||
1478 pred == ICmpInst::ICMP_UGE ||
1479 pred == ICmpInst::ICMP_SGE);
1481 case ICmpInst::ICMP_ULT:
1482 // If we know that C1 < C2, we can decide the result of this computation
1484 Result = (pred == ICmpInst::ICMP_ULT ||
1485 pred == ICmpInst::ICMP_NE ||
1486 pred == ICmpInst::ICMP_ULE);
1488 case ICmpInst::ICMP_SLT:
1489 // If we know that C1 < C2, we can decide the result of this computation
1491 Result = (pred == ICmpInst::ICMP_SLT ||
1492 pred == ICmpInst::ICMP_NE ||
1493 pred == ICmpInst::ICMP_SLE);
1495 case ICmpInst::ICMP_UGT:
1496 // If we know that C1 > C2, we can decide the result of this computation
1498 Result = (pred == ICmpInst::ICMP_UGT ||
1499 pred == ICmpInst::ICMP_NE ||
1500 pred == ICmpInst::ICMP_UGE);
1502 case ICmpInst::ICMP_SGT:
1503 // If we know that C1 > C2, we can decide the result of this computation
1505 Result = (pred == ICmpInst::ICMP_SGT ||
1506 pred == ICmpInst::ICMP_NE ||
1507 pred == ICmpInst::ICMP_SGE);
1509 case ICmpInst::ICMP_ULE:
1510 // If we know that C1 <= C2, we can only partially decide this relation.
1511 if (pred == ICmpInst::ICMP_UGT) Result = 0;
1512 if (pred == ICmpInst::ICMP_ULT) Result = 1;
1514 case ICmpInst::ICMP_SLE:
1515 // If we know that C1 <= C2, we can only partially decide this relation.
1516 if (pred == ICmpInst::ICMP_SGT) Result = 0;
1517 if (pred == ICmpInst::ICMP_SLT) Result = 1;
1520 case ICmpInst::ICMP_UGE:
1521 // If we know that C1 >= C2, we can only partially decide this relation.
1522 if (pred == ICmpInst::ICMP_ULT) Result = 0;
1523 if (pred == ICmpInst::ICMP_UGT) Result = 1;
1525 case ICmpInst::ICMP_SGE:
1526 // If we know that C1 >= C2, we can only partially decide this relation.
1527 if (pred == ICmpInst::ICMP_SLT) Result = 0;
1528 if (pred == ICmpInst::ICMP_SGT) Result = 1;
1531 case ICmpInst::ICMP_NE:
1532 // If we know that C1 != C2, we can only partially decide this relation.
1533 if (pred == ICmpInst::ICMP_EQ) Result = 0;
1534 if (pred == ICmpInst::ICMP_NE) Result = 1;
1538 // If we evaluated the result, return it now.
1540 if (const VectorType *VT = dyn_cast<VectorType>(C1->getType())) {
1542 return Constant::getNullValue(VT);
1544 return Constant::getAllOnesValue(VT);
1546 return ConstantInt::get(Type::Int1Ty, Result);
1549 if (!isa<ConstantExpr>(C1) && isa<ConstantExpr>(C2)) {
1550 // If C2 is a constant expr and C1 isn't, flop them around and fold the
1551 // other way if possible.
1553 case ICmpInst::ICMP_EQ:
1554 case ICmpInst::ICMP_NE:
1555 // No change of predicate required.
1556 return ConstantFoldCompareInstruction(pred, C2, C1);
1558 case ICmpInst::ICMP_ULT:
1559 case ICmpInst::ICMP_SLT:
1560 case ICmpInst::ICMP_UGT:
1561 case ICmpInst::ICMP_SGT:
1562 case ICmpInst::ICMP_ULE:
1563 case ICmpInst::ICMP_SLE:
1564 case ICmpInst::ICMP_UGE:
1565 case ICmpInst::ICMP_SGE:
1566 // Change the predicate as necessary to swap the operands.
1567 pred = ICmpInst::getSwappedPredicate((ICmpInst::Predicate)pred);
1568 return ConstantFoldCompareInstruction(pred, C2, C1);
1570 default: // These predicates cannot be flopped around.
1578 Constant *llvm::ConstantFoldGetElementPtr(const Constant *C,
1579 Constant* const *Idxs,
1580 unsigned NumIdx, bool locked) {
1582 (NumIdx == 1 && Idxs[0]->isNullValue()))
1583 return const_cast<Constant*>(C);
1585 if (isa<UndefValue>(C)) {
1586 const PointerType *Ptr = cast<PointerType>(C->getType());
1587 const Type *Ty = GetElementPtrInst::getIndexedType(Ptr,
1589 (Value **)Idxs+NumIdx);
1590 assert(Ty != 0 && "Invalid indices for GEP!");
1591 return UndefValue::get(PointerType::get(Ty, Ptr->getAddressSpace()),
1595 Constant *Idx0 = Idxs[0];
1596 if (C->isNullValue()) {
1598 for (unsigned i = 0, e = NumIdx; i != e; ++i)
1599 if (!Idxs[i]->isNullValue()) {
1604 const PointerType *Ptr = cast<PointerType>(C->getType());
1605 const Type *Ty = GetElementPtrInst::getIndexedType(Ptr,
1607 (Value**)Idxs+NumIdx);
1608 assert(Ty != 0 && "Invalid indices for GEP!");
1610 ConstantPointerNull::get(PointerType::get(Ty,Ptr->getAddressSpace()),
1615 if (ConstantExpr *CE = dyn_cast<ConstantExpr>(const_cast<Constant*>(C))) {
1616 // Combine Indices - If the source pointer to this getelementptr instruction
1617 // is a getelementptr instruction, combine the indices of the two
1618 // getelementptr instructions into a single instruction.
1620 if (CE->getOpcode() == Instruction::GetElementPtr) {
1621 const Type *LastTy = 0;
1622 for (gep_type_iterator I = gep_type_begin(CE), E = gep_type_end(CE);
1626 if ((LastTy && isa<ArrayType>(LastTy)) || Idx0->isNullValue()) {
1627 SmallVector<Value*, 16> NewIndices;
1628 NewIndices.reserve(NumIdx + CE->getNumOperands());
1629 for (unsigned i = 1, e = CE->getNumOperands()-1; i != e; ++i)
1630 NewIndices.push_back(CE->getOperand(i));
1632 // Add the last index of the source with the first index of the new GEP.
1633 // Make sure to handle the case when they are actually different types.
1634 Constant *Combined = CE->getOperand(CE->getNumOperands()-1);
1635 // Otherwise it must be an array.
1636 if (!Idx0->isNullValue()) {
1637 const Type *IdxTy = Combined->getType();
1638 if (IdxTy != Idx0->getType()) {
1639 Constant *C1 = ConstantExpr::getSExtOrBitCast(Idx0, Type::Int64Ty,
1641 Constant *C2 = ConstantExpr::getSExtOrBitCast(Combined,
1644 Combined = ConstantExpr::get(Instruction::Add, C1, C2, locked);
1647 ConstantExpr::get(Instruction::Add, Idx0, Combined, locked);
1651 NewIndices.push_back(Combined);
1652 NewIndices.insert(NewIndices.end(), Idxs+1, Idxs+NumIdx);
1653 return ConstantExpr::getGetElementPtr(CE->getOperand(0), &NewIndices[0],
1654 NewIndices.size(), locked);
1658 // Implement folding of:
1659 // int* getelementptr ([2 x int]* cast ([3 x int]* %X to [2 x int]*),
1661 // To: int* getelementptr ([3 x int]* %X, long 0, long 0)
1663 if (CE->isCast() && NumIdx > 1 && Idx0->isNullValue()) {
1664 if (const PointerType *SPT =
1665 dyn_cast<PointerType>(CE->getOperand(0)->getType()))
1666 if (const ArrayType *SAT = dyn_cast<ArrayType>(SPT->getElementType()))
1667 if (const ArrayType *CAT =
1668 dyn_cast<ArrayType>(cast<PointerType>(C->getType())->getElementType()))
1669 if (CAT->getElementType() == SAT->getElementType())
1670 return ConstantExpr::getGetElementPtr(
1671 (Constant*)CE->getOperand(0), Idxs, NumIdx, locked);
1674 // Fold: getelementptr (i8* inttoptr (i64 1 to i8*), i32 -1)
1675 // Into: inttoptr (i64 0 to i8*)
1676 // This happens with pointers to member functions in C++.
1677 if (CE->getOpcode() == Instruction::IntToPtr && NumIdx == 1 &&
1678 isa<ConstantInt>(CE->getOperand(0)) && isa<ConstantInt>(Idxs[0]) &&
1679 cast<PointerType>(CE->getType())->getElementType() == Type::Int8Ty) {
1680 Constant *Base = CE->getOperand(0);
1681 Constant *Offset = Idxs[0];
1683 // Convert the smaller integer to the larger type.
1684 if (Offset->getType()->getPrimitiveSizeInBits() <
1685 Base->getType()->getPrimitiveSizeInBits())
1686 Offset = ConstantExpr::getSExt(Offset, Base->getType());
1687 else if (Base->getType()->getPrimitiveSizeInBits() <
1688 Offset->getType()->getPrimitiveSizeInBits())
1689 Base = ConstantExpr::getZExt(Base, Offset->getType(), locked);
1691 Base = ConstantExpr::getAdd(Base, Offset, locked);
1692 return ConstantExpr::getIntToPtr(Base, CE->getType(), locked);